CS835 - Data and Document Representation & Processing

Lecture 12 - Hypermedia VI – Physical Hypermedia

Augmented Reality (AR)

1)     Combines real and virtual

2)     Interactive in real time

3)     Registered in 3D

Real desk with virtual lamp and two virtual chairs


Augment the user

The user wears or carries a device, usually on the head or hands, to obtain information about physical objects.


Augment the physical object

·         The physical object is changed by embedding input, output or computational devices on or within it.

e.g. Electronic bricks contain simple electronic devices such as sensors (light, sound, touch, proximity), logic devices (and-gates, flip-flops, timers) and action bricks (motors, lights).

·         Ubiquitous computing in which specially-created objects are detected by sensors placed throughout the building.


Augment the environment surrounding the user and the object

·         Independent devices provide and collect information from the surrounding environment, displaying information onto objects and capturing information about the user's interactions with them.


o       The Digital Desk uses a video camera to detect where a user is pointing and a close-up camera to capture images of numbers, which are then interpreted via optical character recognition.

o       A projector overhead projects changes made by the user back onto the surface of the desk.

1)     The user may have a column of numbers printed on a particular page.

2)     The user points to numbers, the digital desk reads and interprets them, and then places them into an electronic spreadsheet, which is projected back onto the desk.

3)     Using his fingers, the user can modify the numbers and perform "whatif" calculations on the original data

A user points to a column of numbers printed on a paper document and then uses an electronic calculator projected on the desktop.


·         eTag system - simple connection between physical object and an action or a piece of information on the Web, such as the related Amazon page.

·         FindEntity system [ http://www.thax.de/english/frame.html ] - provides support for locating physical material inside buildings and offices using Radio Frequency Identification (RFID).




Examples of augmented reality approaches, with relevant technologies and applications


AR Applications

Peel back the MRI skin and see where the internal structures are located relative to the viewpoint of the camera

Superposition of MRI Scans on patients


Left Figure: Attached several Logitech 3D trackers (the small triangles in the figure shown
above) to key components of the printer, allowing the system to monitor their position and orientation

Right Figure: shows a virtual world designed by KARMA, viewed ``live'' through a see-through head-mounted display.



Used to annotate objects and environments with public or private information.

The user points at the exhaust manifold on an engine model, and the label "exhaust manifold" appears. 

Windows on the World - 2D Windows for 3D Augmented Reality
Windows attached from a standard user interface onto specific locations in the world

To accomplish the simultaneous capture and display:

Telecubicle - 3D real time acquisition data combined with static 3D background (latter is a laser scan of an office). Remote participant Amela Sadagic in Armonk, NY, and a local participant Wei-Chao Chen in Chapel Hill, NC.


Prototype campus information system.

The user wears a backpack and headworn display, and holds a handheld display and its stylus



Implementation Framework



Physical Hypermedia

Physical Hypermedia: Organizing Collections of Mixed Physical and Digital Material, Kaj Grønbæk, Jannie F. Kristensen, Peter Ørbæk Mette Agger Eriksen


Physical Hypermedia – make objects from physical world into first class objects in hypermedia systems.


Ubiquitous and pervasive computing

·         Main focus to develop infrastructures for dealing with display enabled devices in a variety of different scales, from interactive walls to PDAs, cell phones, and wrist watches etc.

·         Far less focus on how to associate computing with familiar physical artifacts such as paper, folders, binders, models, samples etc. as being used in many work domains


Augmented Reality


Hypermedia and spatial relationships


Challenge of bridging between physical and digital material


Empirical studies:

1)     Landscape architects take different approaches for organizing material depending on the degree of formalization of procedures in terms of work context.

2)     Physical space is not just used for organizing with the purpose of re-finding material

3)     It is also used as an exhibition of ongoing work, as well as the creation of an inspirational and creative atmosphere.






Abstractions of collectional actions


·        Relationships between physical and digital world:

1.      Physical-only: Only physical object, the digital world has no trace of the object, at all.

2.      Physical-with-digital-id: The digital world posses an ID plus some meta-data relating to the physical object but no digital representation; for example: a stone or a brick with an RFID tag on it.

3.      Physical-with-low-resolution-digital representation: a pen tracked drawing, a scanned document or a photo of an object.

4.      Physical-generated-from-digital: a printed map, drawing or report.

5.      Digital-only: Content that cannot be printed or otherwise made physical/tangible, e.g. a video, sound or source files (they may be stored on removable media like CD/DVD, but the content cannot be accessed in the non-digital physical world).



A document object in Topos. A red corner (top left) indicates that a tagged item is linked to it but not present at the tag-reader.


RFID reader: a hand-held that only reads a single tag at a time.


A tube with an associated collection tag is placed on the tag-reader.



·        Representing physical material – snapscanning

Design is a circular behavior

o       a snapshot of a sketch in Topos makes the use of tags more efficient and flexible.


The first working prototype of the “Snapscanner” allowing taking a snapshot and linking a tag to the physical material in one operation.



·        A tooltag is an RFID-tag which is coupled to a command in the Topos hypermedia system rather than to a piece of information.

·        Allows issuing of commands in Topos by placing the physical tooltag on the tag-reader alone or together with a piece of physical material.


Tooltags: specific RFID tags have been associated with commands to be invoked via the tag-reader.


Invoking a command on an object by placing object and tooltag on the RFID reader.




Modeling Physical Hypermedia Applications, Silvia Gordillo Gustavo Rossi Fernando Lyardet


·        Example scenario –

o       Museum in which visitors are equipped with portable computer devices, and there is some location sensing mechanism.

o       When the visitor stands in front of an artwork, he can see its digital representation.

o       He is presented with a set of anchors that allows him to navigate to other nodes (information items) related with the artwork.

o       When one of these nodes represents a physical object, he is informed on how to reach that object (perhaps another artwork);

o       Can choose to traverse the physical space (“walk” the link) towards this node or just continue his tour.

o       Not just augmenting the physical object (artwork) with some digital information but also providing some kind of linking to other digital or physical objects.


·        Approach to model PH applications extends the Object-Oriented Hypermedia Design Method (OOHDM) by adding new abstractions and re-defining the semantics of basic navigational behaviors.


The Design Approach

·        They define a PH application as a hypermedia application (i.e. the access to information objects is done by navigation), in which all or some of the objects of interest are real-world objects which are visited by the user “physically”.

·        They assume that in a PH application there is some underlying location-sensing technology that allows the application to be aware of the actual user’s position.

·        Two different ways to implement hypermedia navigation:

  1. the usual way - selecting an anchor and accessing the target object
  2. physical way - the user must change his position and walk towards the object


·        Must specify unambiguously the system’s intended structure and behavioral semantics.

·        Must express which are the objects of interest and their properties including:

o       their locations

o       how they are linked

o       which links should be implemented as conventional

o       which should be “walked” by the user


Basic Design Framework

·        OOHDM partitions the development space into four activities:

o       conceptual modeling

o       navigation design

o       abstract interface design

o       implementation


·        During conceptual modeling we describe the application classes and their relationships using UML.

o       Focus is placed on generic application’s behavior

o       application is modeled neutrally with respect to navigation issues


·        In OOHDM, a hypermedia or Web application is seen as a navigational view over the conceptual model

o       can specify different views according to the user profile or role.

o       can define a different navigational structure, which will reflect objects and relationships in the conceptual schema according to the tasks this kind of user must perform.

o       The navigational structure of a Web application is defined by a schema, containing navigational classes such as nodes, links, anchors and access structures.


o       The semantics of nodes, links and anchors are as usual in hypermedia applications.

o       Access structures, such as indexes, represent possible ways for starting navigation.


·        The abstract interface model defines which interface objects the user will perceive (in particular how nodes will look like) and which interface transformations will take place.


·        During implementation the whole set of models is mapped into a run-time environment.


·        OOHDM does not prescribe a particular strategy for implementing a hypermedia or Web application

·        The design style facilitates the use of object-oriented languages and architectural styles such as the Model-View-Controller metaphor.


Dealing with physical Objects

·        OOHDM meta-model extended by adding the concept of Physical Object.

·        A physical object is an application object that can be explored “physically”

o       it will have a physical presence in the system

o       we can sense if the user is near it

o       e.g. the museum example  we may be interested in modeling artworks and even rooms as physical objects.

o       Approach for modeling physical objects:

§         consider that not all objects in a class (e.g. Artwork) must be tagged as physical

§         e.g. relate artworks that exist physically with others that are

·        not in exhibition

·        are in another geographical place

·        simply do not exist anymore.

§         Representing physical objects as sub-classes of a particular class (Artwork) introduces a specialization criteria that might collide with others in the intended domain (paintings, sculptures, etc)

o       Chosen to model physical objects as roles that can be assumed by conceptual objects.

§         A role type (in this case “physical”) indicates those properties and behaviors of an object when playing that role.

§         Roles can easily be mapped to implementation settings using for example decorators.


There is a specific role type for each of them.


·        Physical objects are characterized by an attribute position whose semantics depends on the location sensing technology

o       Must be refined for each application

o       Different role types (e.g. Museum and Boutique) might use different ways of location sensing and representation

§         e.g. infrared position technology may require might be implemented using just an identifier,

§         outdoor applications that use GPS or other sensing techniques, position must be implemented using more complex location models.

·        Physical objects implement the inFrontOfMe (user) behavior that is triggered by the underlying software when the user is sensed to be in the object’s vicinity.

o       Standard behavior is to open the corresponding node

o       Also implement the howToReachFrom (location) which is used by walking links to indicate how the user can find the object.


·        Separating the conceptual from the physical aspect of an object :

o       allows decoupling of design decisions

o       allows building of different browsing strategies according to the dimension considered (e.g. physical or digital)


Specifying Navigation aspects

·        The navigation schema shows which nodes the user will perceive and which links he can follow.

·        Nodes are built from conceptual objects and links are derived from relationships in the conceptual model.

·        Cornerstones of OOHDM is that a different navigation schema can be built for different user roles.


·        Museum application - can for example build a different navigation schema for the regular visitor or for an expert (for example a person working in the Museum).

o       Some artworks might be even (physically) inaccessible for a visitor, while the museum worker should be able to access them for performing his work.


·        Differences between a conventional and a physical hypermedia regarding the navigational schema:

o       the activation of nodes

o       the semantics of link traversal

·        Conventional hypermedia - a node is opened when we navigate a link having that node as a target.

o       Preserve this behavior for “pure” digital nodes

o       A node that stands for a physical object should only be opened when the user is facing the object

o       introduced changes in the physical objects (role) classes and in the link class behaviors.


·        Different navigation semantics - walking links (WLinks) - those links whose target node is the digital counterpart of a physical object.

·        Main difference between the operational semantics of a navigational and a walking links:

o       navigational links close the current node and opens the target node

o       walking links indicate the user’s intention to reach the corresponding physical object

·        the link invokes the howToReachFrom behavior in the physical object corresponding to the target node, using as a parameter the current user location.


·        Figure - the navigational schema for the visitor user role that corresponds to the conceptual model.

·        WLinks with a <<W>> in the style of UML stereotypes [10]; as said before we can have “non-walking” instances of a WLink simply by specifying it at the instance level.